mm: memcg: inline mem_cgroup_charge_common()

mem_cgroup_charge_common() is used by both cache and anon pages, but
most of its body only applies to anon pages and the remainder is not
worth having in a separate function.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -3887,20 +3887,21 @@ static int mem_cgroup_move_parent(struct page *page,
 	return ret;
 }
 
-/*
- * Charge the memory controller for page usage.
- * Return
- * 0 if the charge was successful
- * < 0 if the cgroup is over its limit
- */
-static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
-				gfp_t gfp_mask, enum charge_type ctype)
+int mem_cgroup_newpage_charge(struct page *page,
+			      struct mm_struct *mm, gfp_t gfp_mask)
 {
 	struct mem_cgroup *memcg = NULL;
 	unsigned int nr_pages = 1;
 	bool oom = true;
 	int ret;
 
+	if (mem_cgroup_disabled())
+		return 0;
+
+	VM_BUG_ON_PAGE(page_mapped(page), page);
+	VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
+	VM_BUG_ON(!mm);
+
 	if (PageTransHuge(page)) {
 		nr_pages <<= compound_order(page);
 		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
@@ -3914,22 +3915,11 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
 	ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);
 	if (ret == -ENOMEM)
 		return ret;
-	__mem_cgroup_commit_charge(memcg, page, nr_pages, ctype, false);
+	__mem_cgroup_commit_charge(memcg, page, nr_pages,
+				   MEM_CGROUP_CHARGE_TYPE_ANON, false);
 	return 0;
 }
 
-int mem_cgroup_newpage_charge(struct page *page,
-			      struct mm_struct *mm, gfp_t gfp_mask)
-{
-	if (mem_cgroup_disabled())
-		return 0;
-	VM_BUG_ON_PAGE(page_mapped(page), page);
-	VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
-	VM_BUG_ON(!mm);
-	return mem_cgroup_charge_common(page, mm, gfp_mask,
-					MEM_CGROUP_CHARGE_TYPE_ANON);
-}
-
 /*
  * While swap-in, try_charge -> commit or cancel, the page is locked.
  * And when try_charge() successfully returns, one refcnt to memcg without
@@ -4047,9 +4037,11 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
 	if (PageCompound(page))
 		return 0;
 
-	if (!PageSwapCache(page))
-		ret = mem_cgroup_charge_common(page, mm, gfp_mask, type);
-	else { /* page is swapcache/shmem */
+	if (!PageSwapCache(page)) {
+		ret = __mem_cgroup_try_charge(mm, gfp_mask, 1, &memcg, true);
+		if (ret != -ENOMEM)
+			__mem_cgroup_commit_charge(memcg, page, 1, type, false);
+	} else { /* page is swapcache/shmem */
 		ret = __mem_cgroup_try_charge_swapin(mm, page,
 						     gfp_mask, &memcg);
 		if (!ret)